Every time you launch Thunderbird, you are greeted by a generic start page (unless you've turned that option off). Most of us don't pay much attention to it and navigate straight to the Inbox without giving it a second thought. The start screen is just a simple HTML page, which Thunderbird fetches from the address specified in the application's preferences. Knowing that, you can replace it with something more useful, such as the URL of your Web site or blog -- or you can take it a step further and turn the start screen into a tool that can help to manage your ideas, notes, to-do lists, and more.
First of all, you have to download the latest version of TiddlyWiki and save it somewhere on your local hard disk (your home directory is a good choice). Rename the downloaded file called empty.html to something more meaningful, such as tiddlywiki.html.
Next, launch Thunderbird and choose Edit -> Preferences and click on the General Tab. Make sure that the "When the Thunderbird launches" check box is ticked, and type the path to the tiddlywiki.html file. It should look something like this: file:///home/user/tiddlywiki.html (where "user" is your user name).
Now, restart Thunderbird, and you will be greeted by TiddlyWiki, and you can start filling it up with content. When you navigate away from the start page, you can always get back to it by choosing Go -> Mail Start Page.